package com.lw.test.lmx;

import java.util.HashMap;
import java.util.Map;

/**
 * create by idea
 *
 * @author lmx
 * @version 1.0
 * @date 2022/3/13 15:57
 */
public class FindTheDifference {
    public static void main(String[] args) {
        FindTheDifference test = new FindTheDifference();
        String s = "abcd";
        String t = "abcde";
        char theDifference = test.findTheDifference(s, t);
        System.out.println(theDifference);


    }

    public char findTheDifference(String s, String t) {
        int a=s.length();
        if(a==0){
            return t.charAt(0);
        }
        int b=t.length();

        HashMap<Character, Integer> mapa = new HashMap<>();
        HashMap<Character, Integer> mapb = new HashMap<>();
        for (int i = 0; i < a; i++) {
            char c=s.charAt(i);
            Integer count=mapa.get(c);
            if(count==null){
                mapa.put(c,1);
            }else{
                mapa.put(c,count+1);
            }
        }

        for (int i = 0; i < b; i++) {
            char c=t.charAt(i);
            Integer count=mapb.get(c);
            if(count==null){
                mapb.put(c,1);
            }else{
                mapb.put(c,count+1);
            }
        }

        for (Map.Entry<Character, Integer> entry : mapb.entrySet()) {
            Character key = entry.getKey();
            Integer value = entry.getValue();
            Integer integer = mapa.get(key);
            if(integer==null||integer+1==value){
                return key;
            }
        }
        return ' ';
    }


}
